This application is based on patent application Ser. No. 30135/1997 filed Feb. 14, 1997 in Japan, the content of which is incorporated hereinto by reference.
Field of the Invention
The present invention relates generally to an ink-jet printing apparatus and a printing method, by which a high quality image can be obtained on a printing medium. More specifically, the invention relates to an ink-jet printing apparatus and a printing method, in which a processing liquid making a component contained in an ink insoluble or coagulated is ejected before or after ejection of the ink.
The present invention is applicable for all apparatus using paper, cloth, leather, OHP film, other metals and the like as a printing medium. Particular applicable apparatus are business machines, such as a printer, a copy machine, a facsimile, industrial production machines and so on.
Conventionally, an ink-jet printing method has been widely employed in a printer, a copy machine and so on for easiness of lowering of noise, lowering of a running cost, down-sizing of apparatus, providing capability of color printing of a printing image and for other reasons.
However, in the printing apparatus utilizing such ink-jet printing method, when an image is printed on a plain paper, the water resistance of the image can be insufficient. On the other hand, when a color image is to be printed, it has been not possible to achieve both of a high density image causing no feathering and an image not causing blotting between colors. Thus, it has been difficult to obtain a satisfactory fastness of the image and a sufficiently high quality of color image.
On the other hand, in the recent years, as a method for improving water resistance of the printed image, an ink, in which a coloring agent contained therein is provided with a water resistance, has been practiced. However, the water resistance of the ink is still insufficient. In addition, such ink is principally an ink to be difficult to be solved in water after drying to easily cause plugging with ejection openings of a printing head and thus to make construction complicate for a measure to prevent plugging.
Also, in the prior art, there has been proposed technologies for improving fastness by preliminary process or post-process of the printing medium. The preliminary process is to provide certain processes on the printing medium before printing of the image by the ink. The post-process is to provide certain process on the printing medium after printing the image by the ink.
However, in the prior art set forth above, no consideration has been given for the possibility of the occurrences of differences of printing quality when both preliminarily process portions and post-process portions are present on the printing medium in admixing manner, and for preventive measures therefor.
It is an object of the present invention to discriminate a preliminary process for ejecting an ink after preliminarily ejecting a processing liquid and a post-process for ejecting the processing liquid after ejecting the ink, to restrict a different of printing quality in a preliminary process portion and a post-process portion on a printing medium.
In a first aspect of the present invention, there is provided an ink-jet printing apparatus using an ink ejecting head capable of ejecting an ink, and a processing liquid ejecting head capable of ejecting a processing liquid which makes a coloring agent in the ink insoluble or coagulated, an ink dot being formed on a printing medium by the ink ejected from the ink ejecting head, and a processing liquid dot being formed on the printing medium by the processing liquid ejected from the processing liquid ejecting head, for forming a preliminarily process portion, in which the ink dot is formed after formation of the processing liquid dot, and a post-process portion, in which the processing liquid dot is formed after formation of the ink dot, the apparatus comprising:
control means for differentiating at least one of an ejection amount of the ink per unit area and an ejection amount of the processing liquid per unit area between the preliminarily process portion and the post-process portion.
In a second aspect of the present invention, there is provided an ink-jet printing method using an ink ejecting head capable of ejecting an ink, and a processing liquid ejecting head capable of ejecting a processing liquid which makes a coloring agent in the ink insoluble or coagulated, an ink dot being formed on a printing medium by the ink ejected from the ink ejecting head, and a processing liquid dot being formed on the printing medium by the processing liquid ejected from the processing liquid ejecting head, for forming a preliminarily process portion, in which the ink dot is formed after formation of the processing liquid dot, and a post-process portion, in which the processing liquid dot is formed after formation of the ink dot, the method comprising the step of:
differentiating at least one of an ejection amount of the ink per unit area and an ejection amount of the processing liquid per unit area between the preliminarily process portion and the post-process portion.
By the present invention, when the preliminary process portions for ejecting an ink after ejecting the processing liquid on the printing medium and the post-process portions for ejecting a processing liquid after ejecting the ink are present on the printing medium in admixing manner, at least one of an ejection amount of the ink or an ejection amount of the processing liquid per unit area of the preliminary process portion and the post-process portion is differentiated, to restrict the difference of a printing quality on the preliminary process portion and the post-process portion.